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Message-ID: <CAP-5=fVK6w3Ck_F0gEPrSt6-UuAVUruLmnutJa=LbMO+MxazNg@mail.gmail.com>
Date: Wed, 26 Jun 2024 10:54:07 -0700
From: Ian Rogers <irogers@...gle.com>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Kan Liang <kan.liang@...ux.intel.com>, John Garry <john.g.garry@...cle.com>,
Will Deacon <will@...nel.org>, James Clark <james.clark@....com>,
Mike Leach <mike.leach@...aro.org>, Leo Yan <leo.yan@...ux.dev>,
Suzuki K Poulose <suzuki.poulose@....com>, Yicong Yang <yangyicong@...ilicon.com>,
Jonathan Cameron <jonathan.cameron@...wei.com>, Nick Terrell <terrelln@...com>,
Nick Desaulniers <ndesaulniers@...gle.com>, Oliver Upton <oliver.upton@...ux.dev>,
Anshuman Khandual <anshuman.khandual@....com>, Song Liu <song@...nel.org>,
Ilkka Koskinen <ilkka@...amperecomputing.com>, Huacai Chen <chenhuacai@...nel.org>,
Yanteng Si <siyanteng@...ngson.cn>, Sun Haiyong <sunhaiyong@...ngson.cn>,
linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v1 22/26] perf auxevent: Add explicit dummy tool initialization
On Tue, Jun 25, 2024 at 11:59 PM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 25/06/24 20:25, Ian Rogers wrote:
> > Ensure tool is initialized to avoid lazy initialization pattern so
> > that more uses of struct perf_tool can be made const.
>
> This does not look necessary.
>
> The dummy tool is not used, and is not subject to lazy initialization,
> so the existing initialization to zero is fine.
Thanks, I wonder if we should try to save space in this case with
something like:
```
struct intel_pt_synth {
struct perf_session *session;
struct perf_tool dummy_tool[0];
};
```
I'll play around while dropping the initialization calls.
Thanks,
Ian
> >
> > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > ---
> > tools/perf/util/arm-spe.c | 1 +
> > tools/perf/util/cs-etm.c | 1 +
> > tools/perf/util/intel-bts.c | 1 +
> > tools/perf/util/intel-pt.c | 2 +-
> > tools/perf/util/s390-cpumsf.c | 1 -
> > 5 files changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
> > index 70bad18c4a0d..06a198b2f483 100644
> > --- a/tools/perf/util/arm-spe.c
> > +++ b/tools/perf/util/arm-spe.c
> > @@ -1097,6 +1097,7 @@ static int arm_spe_synth_event(struct perf_session *session,
> >
> > memset(&arm_spe_synth, 0, sizeof(struct arm_spe_synth));
> > arm_spe_synth.session = session;
> > + perf_tool__init(&arm_spe_synth.dummy_tool, /*ordered_events=*/false);
> >
> > return perf_event__synthesize_attr(&arm_spe_synth.dummy_tool, attr, 1,
> > &id, arm_spe_event_synth);
> > diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> > index 231cd833c012..02eb5b3eed14 100644
> > --- a/tools/perf/util/cs-etm.c
> > +++ b/tools/perf/util/cs-etm.c
> > @@ -1619,6 +1619,7 @@ static int cs_etm__synth_event(struct perf_session *session,
> >
> > memset(&cs_etm_synth, 0, sizeof(struct cs_etm_synth));
> > cs_etm_synth.session = session;
> > + perf_tool__init(&cs_etm_synth.dummy_tool, /*ordered_events=*/false);
> >
> > return perf_event__synthesize_attr(&cs_etm_synth.dummy_tool, attr, 1,
> > &id, cs_etm__event_synth);
> > diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
> > index 779982c478e0..ae97109542be 100644
> > --- a/tools/perf/util/intel-bts.c
> > +++ b/tools/perf/util/intel-bts.c
> > @@ -761,6 +761,7 @@ static int intel_bts_synth_event(struct perf_session *session,
> >
> > memset(&intel_bts_synth, 0, sizeof(struct intel_bts_synth));
> > intel_bts_synth.session = session;
> > + perf_tool__init(&intel_bts_synth.dummy_tool, /*ordered_events=*/false);
> >
> > return perf_event__synthesize_attr(&intel_bts_synth.dummy_tool, attr, 1,
> > &id, intel_bts_event_synth);
> > diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> > index bed35029e1f6..48ed60e521ed 100644
> > --- a/tools/perf/util/intel-pt.c
> > +++ b/tools/perf/util/intel-pt.c
> > @@ -3687,7 +3687,7 @@ static int intel_pt_synth_event(struct perf_session *session, const char *name,
> >
> > memset(&intel_pt_synth, 0, sizeof(struct intel_pt_synth));
> > intel_pt_synth.session = session;
> > -
> > + perf_tool__init(&intel_pt_synth.dummy_tool, /*ordered_events=*/false);
> > err = perf_event__synthesize_attr(&intel_pt_synth.dummy_tool, attr, 1,
> > &id, intel_pt_event_synth);
> > if (err)
> > diff --git a/tools/perf/util/s390-cpumsf.c b/tools/perf/util/s390-cpumsf.c
> > index 5834bad6ac0f..eb835e531cd6 100644
> > --- a/tools/perf/util/s390-cpumsf.c
> > +++ b/tools/perf/util/s390-cpumsf.c
> > @@ -953,7 +953,6 @@ s390_cpumsf_process_event(struct perf_session *session,
> > }
> >
> > struct s390_cpumsf_synth {
> > - struct perf_tool cpumsf_tool;
> > struct perf_session *session;
> > };
> >
>
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